Organic electroluminescent devices are light emitting devices that are based on the passage of current through one or multiple organic thin layers. FIG. 1 shows a conventional structure. For polymer materials, it is possible to make a single layer organic device sandwiched between a cathode 1 and an anode 6. However, most organic devices are multilayer in nature. Usually, a hole transport layer 4 (HTL) and an electron transport layer 3 (ETL) are needed. One of these electron or hole transport layers can be the light emitting layer (EML), or another light emitting layer 9 (FIG. 2) is deposited between the ETL and the HTL. Examples of typical hole transport materials are TPD and NPB. Examples of electron transport materials are Alq3 and Bphen. Alq3 and doped Alq3 are usually used as the light emitting layer. Much work has been devoted to the optimization of the device structure in terms of the thicknesses of the various layers, and in synthesizing new materials that are more efficient in transporting the carriers and in generating light emission.